The present invention relates to methods of and apparatus for determining blood losses during endoscopic operations, and especially during urethral resectomy, of the kind in which continuous irrigation is employed, using sterilised water which is fed into the body cavity through the endoscope and is fed out again mixed with the blood which has been lost.
During endoscopic operations, and particularly during transurethral electrical resectomy, losses of blood occur if blood vessels are cut into and it is essential for these to be kept within bounds by deliberately coagulating the blood vessels at the appropriate points. If, during resectomy in the bladder for example, the irrigating water became heavily impregnated with blood and as a result the vision of the operator was obscured, then with conventional instruments the bladder was emptied and filled again with clean sterilised water. From the number of filling operations and the discoloration of the irrigating water in each case, which is dependant on the amount of blood present, it was possible for an experienced operator to estimate the blood losses and if necessary give a blood transfusion.
However, the introduction of resectoscopes designed for continuous irrigation means that it is no longer possible to estimate blood losses on the basis of experience. The fact is that even when there is severe bleeding from large vessels, then because of the continuous flushing vision is never impaired during the resection and the operator has no clue to help him to answer the question of how much blood is being lost at any given time and when it is necessary to coagulate an injured blood vessel. In particular, the fact that the viewing conditions are at all times good may tempt an inexperienced operator to carry on with the resection uninterruptedly, without coagulating larger vessels if this has become necessary in the meantime. This may have serious consequences particularly if so-called sinus bleeding occurs, which may not be realised immediately because of the continuously good viewing conditions.
It is an object of the invention to provide a method of and apparatus for determining blood losses during endoscopic operations which, despite the use of continuous irrigation, at all times give the operator an accurate indication of the instantaneous, and if required the total, blood loss and makes it easier for him to decide, as he could previously only do empirically, whether vessels have to be coagulated or even whether a blood transfusion has to be given.